diff --git a/.github/workflows/compilers.yml b/.github/workflows/compilers.yml
index 2188bfad331801..e9b5e882c2ae71 100644
--- a/.github/workflows/compilers.yml
+++ b/.github/workflows/compilers.yml
@@ -258,7 +258,11 @@ jobs:
 
       - run: make
 
-      - run: make test
+      - run: make test BTESTS=-j1
+        env:
+          RUBY_DEBUG_LOG: /tmp/log
+          RUBY_DEBUG_LOG_FILTER=pthread
+          RUBY_ON_BUG='cat /tmp/log '
 
       - run: make install
         if: ${{ matrix.entry.check }}
diff --git a/vm_debug.h b/vm_debug.h
index 9c7fc65f7c1f92..56f7b8889ac2ec 100644
--- a/vm_debug.h
+++ b/vm_debug.h
@@ -32,7 +32,7 @@ void ruby_set_debug_option(const char *str);
 RUBY_SYMBOL_EXPORT_END
 
 #ifndef USE_RUBY_DEBUG_LOG
-#define USE_RUBY_DEBUG_LOG 0
+#define USE_RUBY_DEBUG_LOG 1
 #endif
 
 /* RUBY_DEBUG_LOG: Logging debug information mechanism